Extensive topographical reorganization occurs in mammalian visual areas following a retinal lesion. This reorganization is most robust following months of recovery; however, the adaptive cortical mechanisms driving this reorganization are initiated within seconds of visual deafferentation (short-term plasticity). Very little is known abut short-term plasticity in the human visual system and even less is known about the role of feedback from higher-order visual areas in these processes. The proposed project will investigate the neural mechanisms of short-term plasticity in the human visual system, focusing on the role of cortico-cortical feedback projections. A perceptually-induced retinal scotoma (artificial scotoma) will be used to safely mimic the short-term effects of a retinal lesion. Resultant changes in visual cortical response properties will be measured using a combination of event-related potentials (ERP), transcranial magnetic stimulation (TMS), and psychophysical measurements. At the conclusion of this project we will have an understanding of the spatiotemporal dynamics of feedback in short-term plasticity and the cortical origins of these feedback signals.